JPH0156084B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a curable resin having an unsaturated group in a side chain via an ester bond, which is useful for various uses such as molding materials, FRP, adhesives, and paints. [Prior art] Typical radical curable resins are unsaturated polyester resins and vinyl ester resins.
Diaryl phthalate resins are also used in molding materials, decorative laminates, and the like. Each of these resins is used according to its features and physical properties and is extremely useful. On the other hand, even in various applications and when new properties are required, there are many points in which existing drawbacks must be improved. For example, vinyl ester resin has excellent water resistance,
Although it exhibits chemical resistance and is widely used as corrosion-resistant FRP and corrosion-resistant flake lining, it is currently difficult to produce molding materials or fiber-based prepregs and obtain useful molded products. It's summery. That is, depending on the application, if the molecular weight of an oligomer or prepolymer is from several hundred to 2,000, it is difficult to apply it to the production of a molding material or prepreg, and it is necessary to increase the molecular weight by some means. Therefore, taking the above-mentioned vinyl ester resin as an example, in order to increase the viscosity, it is common to use diisocyanate in combination and react with the hydroxyl groups in the vinyl ester resin to increase the molecular weight. ing. However, when using isocyanates, this method generally tends to have a certain viscosity, fluidity,
It is difficult to obtain moldability and there is considerable variation. Furthermore, because it is chemically crosslinked, it tends to be difficult to mold, which is a strong factor preventing its widespread use. In addition, although the increase in viscosity due to the formation of metal crosslinks caused by the combination of the carboxyl group at the end of the molecule and the oxide of a divalent metal such as magnesia, which occurs in unsaturated polyester resins, has recently become controllable, the moldability There still remains some variation, and in applications where high electrical properties are required, the use of alkaline metal oxides may be discouraged. [Problems to be Solved by the Invention] The present invention improves the various drawbacks of the existing resins described above, and is one of the curable resins whose uses have been expanded. Even though vinyl copolymer resin has unsaturated bonds via ester bonds and is a curable resin with excellent physical properties such as water resistance and impact resistance, organic solvents are used in part of the reaction process. The purpose of the present invention is to provide a method for producing a curable resin that solves problems such as the recovery and resin refining of the curable resin requiring complicated processes, which inevitably result in high costs and which are not desirable from the viewpoint of resin quality control. be. [Means for solving the problems] The method for producing a curable resin of the present invention comprises at least one
A mixture of an ethylene monomer having an esterification reactive group selected from (meth)acrylic acid or mono(meth)acrylate of an epoxy resin and a vinyl monomer selected from styrene, acrylonitrile, or (meth)acrylic acid ester as a component. A vinyl copolymer having the reactive group in the side chain is produced by polymerization, and then the obtained vinyl copolymer and an ethylene-based unsaturated compound having a functional group that forms an ester bond with the reactive group are produced. When the monomer is (meth)acrylic acid, it is epoxy resin mono(meth)acrylate, and when it is epoxy resin mono(meth)acrylate, it is (meth)acrylate.
In a method for producing a curable resin having an unsaturated bond in a side chain via an ester bond by reacting acrylic acid with the reactive group and the functional group in a substantially equivalent ratio, the vinyl-based The above problem was solved by copolymerizing a mixture of monomers by bulk polymerization until a vinyl copolymer having a weight average molecular weight of 5,000 to 200,000 was obtained. [Function] The method of the present invention is the first step in the production of curable resin.
In the step step, that is, the copolymerization step to obtain a vinyl copolymer having an esterification reaction group in the side chain (hereinafter referred to as a vinyl copolymer), the weight average molecular weight
By copolymerizing by bulk polymerization until a vinyl copolymer of 5,000 to 200,000 is produced, complicated steps associated with the use of solvents are not required, and even though no solvent is used, the reactants are eliminated during the entire process. We have arrived at a method that does not cause gelation and is easy to operate. Generally speaking, bulk polymerization is a well-known polymerization method for obtaining vinyl polymers. However, bulk polymerization has drawbacks such as the control of heat generation in vinyl polymerization and the inconvenience of handling when the product is a solid. When conducting a chemical reaction, it was necessary to use a solvent in the first step in order to avoid the above-mentioned difficulties. Simply applying bulk polymerization to the first stage copolymerization does not solve the aforementioned problems such as difficulty in controlling the reaction, generation of gel, and inconvenience in handling the reaction product. The method of the present invention, when performing bulk polymerization, produces a copolymer with a molecular weight lower than that of the polymer produced in ordinary vinyl polymerization, so that the product is convenient to handle, no gel is generated, and bulk polymerization is possible. This is based on the knowledge that it is easy to control the reaction heat and that it is possible to obtain a curable resin with good physical properties. According to the method of the present invention, since the molecular weight of the vinyl copolymer produced is suppressed to a low molecular weight, the increase in viscosity accompanying an increase in the polymerization rate is small, and there are advantages that bulk polymerization can be easily carried out. The second advantage is that the unreacted vinyl monomer can be used as it is as a solvent in the second step, and can also be used as a crosslinking agent for the curable resin. The molecular weight (weight average) of the vinyl copolymer produced in the first step of the method of the present invention is 5,000 to 200,000.
It is adjusted to the range of . If the molecular weight is lower than 5,000, the physical properties of the cured resin, especially the impact resistance, will be low, and if the molecular weight is higher than 200,000, the reaction solution will become highly viscous and the product will be inconvenient to handle, so it is preferable. do not have. A vinyl copolymer with such a molecular weight can be used at a reaction temperature of
1 to 200°C, preferably in the presence of a molecular weight regulator.
Obtained by copolymerizing a mixture of vinyl monomers for 10 hours. Molecular weight modifiers that can be used in the method of the present invention are not particularly limited, but include:
Methyl mercaptan, ethyl mercaptan, n-
or i-propyl mercaptan, n-, sec-,
or alkyl mercaptans such as t-butyl mercaptan, n- or i-dodecyl mercaptan, adducts of alkylene oxide and hydrogen sulfide such as ethanethiol and propanethiol, 2-
Thiol-based molecular weight regulators such as mercapto-substituted fatty acids such as mercaptoacetic acid and 2-mercaptopropionic acid are particularly suitable;
It is added in a proportion of 0.1 to 5 parts by weight per 100 parts by weight. The copolymerization reaction can be carried out by adding a radical generator commonly used in radical polymerization, but it is better to carry out thermal polymerization without a catalyst by heating only, since there is no residual catalyst in the second step, so the polymerization inhibitor is added. This is advantageous because it acts extremely effectively and prevents gelation. As the copolymerization reaction progresses, a sample of the reaction solution is taken periodically to measure the molecular weight, and when the desired molecular weight is reached, a polymerization inhibitor and a diluent monomer are added to stop the copolymerization reaction. The mixture of vinyl monomers used to produce the vinyl copolymer of the present invention must contain an ethylene monomer having an esterification reactive group as at least one component. Here, the esterification reaction group means a functional group that generates an ester bond through a reaction with another functional group such as an addition reaction or a condensation reaction, and specifically includes a carboxyl group and an epoxy group. Representative examples of ethylene monomers having esterification reactive groups include acrylic acid, methacrylic acid, and mono(meth)acrylates of epoxy resins. The vinyl monomer copolymerized with the ethylene monomer having an esterification reaction group includes styrene, acrylonitrile, acrylic ester,
Methacrylic acid esters are practical, and copolymers of them with mono(meth)acrylates of bisphenolic epoxy resins are particularly preferred because they produce curable resins that give excellent cured products. The esterification reactive group introduced into the vinyl copolymer is such that the esterification reactive group in the vinyl monomer mixture is 0.1 to 10 mol%, more preferably 1 to 5 mol%, in the copolymer. It is controlled by mixing ethylene-based monomers. The vinyl copolymer obtained in the first step of the present invention is treated as an unsaturated compound having an esterification reaction group present in its side chain and a functional group that forms an ester bond in the second step. When the ethylene monomer is (meth)acrylic acid, the side chain is reacted with mono(meth)acrylate of epoxy resin, and when mono(meth)acrylate of epoxy resin is reacted with (meth)acrylic acid. It is modified into a curable resin having unsaturated bonds via ester bonds. The reaction for producing this ester bond (hereinafter referred to as esterification) is carried out in the presence of a polymerization inhibitor and an esterification catalyst at a temperature of 50 to 150° C. using a conventional esterification operation. The reaction ratio between the vinyl copolymer and the unsaturated compound should be such that the esterification reaction group present in the copolymer and the esterification functional group in the unsaturated compound are substantially equivalent. is preferable, and it is practically acceptable to react in a range of 0.9 to 1.1 equivalents. Polymerization inhibitors used in the second step include hydroquinone, hydroquinone monomethyl ether, t-butylcatechol, and phenothiazine, and esterification catalysts include tertiary amines, amine salts, quaternary ammonium salts, and metal salts. etc. are preferably used. The curable resin according to the present invention can be cured by copolymerizing with a monomer as a monomer solution, or can be crosslinked by polymerizing the unsaturated bonds of the polymer without using a monomer in combination. Representative examples of the above monomers include styrene, vinyltoluene, chlorostyrene, methyl acrylate, ethyl acrylate, n-butyl acrylate,
Isobutyl acrylate, tertiary butyl acrylate,
2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 3-methacrylate
Examples include butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, tetrahydrofurfuryl methacrylate, vinyl acetate, and vinyl propionate. Furthermore, the curable resin of the present invention may contain fillers, reinforcing materials, mold release agents, colorants, curing agents, accelerators,
It can be widely used in FRP, laminates, adhesives, molding materials, etc. in combination with stabilizers, etc. [Example] Examples will be described below to further specifically explain the present invention. Descriptions in the text are expressed on a weight basis unless otherwise specified. Example 1 3 autoclaves capable of heating and cooling,
Butyl acrylate, acrylic acid, t-dodecyl mercaptan (abbreviated as t-DM), and n-dodecyl mercaptan (abbreviated as n-DM) in the amounts listed in Table 1 were charged, and copolymerization was carried out at 120°C. Summer.
To monitor the progress of copolymerization, approximately 5 g of sample was periodically taken and the molecular weight was measured. When a predetermined molecular weight was reached, ethylene glycol diacrylate (abbreviated as EGDA) as a diluent monomer, phenothiazine as a polymerization inhibitor, and triphenylphosphine as a catalyst were added in the amounts listed in Table 1, respectively. Next, an alicyclic epoxy resin with an epoxy equivalent of 142 (manufactured by Union Carbide, trade name: ERL) was used.
4221) An equivalent amount of an unsaturated epoxy resin that shares an acryloyl group and an epoxy group was added to the molecule obtained by reacting 394 parts of acrylic acid with 160 parts of acrylic acid, and the mixture was heated at 100°C.
The esterification reaction was carried out for about 6 hours. The viscosity of the resulting curable resin liquid was 23 poise (25°C). 100 parts of the above-mentioned curable resin Perkyure SA (peroxide catalyst manufactured by Nippon Oil & Fats Co., Ltd.)
1.5 parts cobalt naphthenate (contains 6% cobalt)
The physical properties of the cured product obtained by mixing 0.5 parts and curing at room temperature were as shown in Table 1. Example 2 A curable resin was produced in the same manner as in Example 1, except that the amounts of t- and n-dodecyl mercaptan used as molecular weight regulators were changed as shown in Table 1. The physical properties of the obtained cured resin were as shown in Table 1. Comparative Example 1 For comparison with Examples 1 and 2, 5 g of 2,2'-azobisisobutyronitrile (abbreviated as AIBN) was used as a polymerization catalyst without using a molecular weight regulator, and at 70°C. Copolymerization and esterification were carried out in the same manner as in Example 1, except that a copolymer having a molecular weight of 220,000 was produced. Approximately 50 minutes after starting esterification, the reaction solution turned into a gel, making it impossible to continue the reaction.

【table】

[Table] Examples 3 to 4 and Comparative Example 2 Styrene and epoxy resin monomethacrylate (bisphenol A type epoxy resin with an epoxy equivalent of 185 (manufactured by Ciel Chemical Co., Ltd.,
Copolymerization was carried out in a manner similar to that described in Example 1 using 462 parts of Epikote 827 (trade name) and 43 parts of methacrylic acid. Example 1 was carried out using the recipe and conditions listed in Table 2, except that when the predetermined molecular weight was reached, the copolymerization was stopped using styrene as the diluent monomer, and then esterification was performed using methacrylic acid. Copolymerization and esterification were carried out in the same manner. The obtained resin liquid and its cured product are shown in Table 2. In the table, the boiling resistance test is performed on a 50 x 50 x 2 (mm) plate.
This is the result of measuring the change in weight after boiling in water for an hour. In addition, when copolymerized to a molecular weight of 240,000 using the same method, it gelled in about 20 minutes after starting esterification, making subsequent reactions impossible.

【table】

〔Effect of the invention〕

According to the method of the present invention, it is possible to produce a curable resin that does not cause gelation and has an unsaturated group in the side chain via an ester bond without using a solvent, and the resulting resin has water resistance and resistance. Provides a cured product with excellent impact resistance, etc., and can be used for adhesives, paints, molding materials, laminates,
It is useful for various uses such as FRP.

Claims (1)

[Scope of Claims] 1. An ethylene monomer having an esterification reactive group selected from (meth)acrylic acid or a mono(meth)acrylate of an epoxy resin as at least one component, and styrene, acrylonitrile, or a (meth)acrylic acid ester. A vinyl copolymer having the reactive group in the side chain is produced by copolymerizing a mixture of vinyl monomers selected from When the ethylene monomer is (meth)acrylic acid, mono(meth)acrylate of epoxy resin is used as the unsaturated compound having a group, and (meth)acrylic acid is used when mono(meth)acrylate of epoxy resin is used. In a method for producing a curable resin having an unsaturated bond in a side chain via an ester bond by reacting the reactive group and the functional group in a substantially equivalent ratio, the vinyl monomer mixture is A method for producing a curable resin, which comprises copolymerizing by bulk polymerization until a vinyl copolymer having an average molecular weight of 5,000 to 200,000 is obtained. 2. The method for producing a curable resin according to claim 1, wherein the bulk polymerization is carried out in the presence of a molecular weight regulator. 3. The method for producing a curable resin according to claim 1 or 2, wherein the bulk polymerization is carried out without a catalyst.